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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Tuesday 6th December 2011 

I used to have a business associate who came from a comparatively wealthy background. Certainly compared to me it was a very wealthy background. Chatting idly, waiting for a ‘plane, one day, we talked about what, when we were very young children, triggered the realisation that Christmas was getting close. For her, it was that the butcher delivered more meat.

These days, for me, a sure sign that the Christmas season has started is the sudden rush of articles, in print and online, about poinsettia, Euphorbia pulcherrima. These articles fall into one of two camps; they state that poinsettia is a deadly poison and children have been killed after eating just a couple of leaves or they state, with equal insistence, that poinsettia is not poisonous.

Euphorbia pulcherrima, poinsettia

Both are wrong.

Poinsettia is in the Euphorbia genus and every plant in that genus is poisonous. It would be remarkable if poinsettia were the exception. The Euphorbia genus is in the Euphorbiaceae family. Another well-known genus in that family is Ricinus communis, the castor oil plant, so there’s toxicity in the genes.

But, being poisonous is not the same thing as being harmful. Those who claim that poinsettia is a danger to children if brought into the home at Christmas are missing this important difference. It is sometimes said that children have died but without offering any support for that statement. Other writers will quote a single case where death was said to be due to poinsettia poisoning but a re-examination of the case records clearly showed that this was the wrong conclusion. (It would seem that there was a poinsettia plant in the house but no evidence that the child had eaten any of it. That's similar to the situation, in the 1970s, when children ended up getting their stomach's pumped just because they were found standing close to a Laburnum tree.)

Then there is the phenomenon I’ve commented on before where, because people think a plant is dangerous, poison control centres receive more calls about it than other plants of similar toxicity. When that understandable situation is taken up by writers who would have you believe that calls to poison control centres equals poisonings, you get the spread of the perception that having poinsettia around children is a very bad idea.

So, it is absolutely untrue to say Euphorbia pulcherrima is a serious hazard.

But, it is equally untrue to say it is not poisonous. In this case, the confusion comes from thinking not harmful is the same thing as not poisonous. It isn’t and most of the people who say poinsettia isn’t poisonous show this in their articles but don’t acknowledge it.

Euphorbia pulcherrima, poinsettia

A typical explanation will go; ‘poinsettia is not poisonous but eating a large quantity of the leaves could cause a stomach upset’. To most people, eating something that produces illness is poisoning. That’s almost how poison is defined.

A frequently cited source for the ‘poinsettia is not poisonous’ stories is the Snopes website. If you’re not familiar with it, it looks, mostly, at the sort of tales that get circulated by email and examines whether they are true or not. Knowing how quickly people want answers from websites, Snopes always gives its conclusion before its evidence. Thus the poinsettia page says ‘Poinsettia plants are poisonous to humans – false’ at the top. If, however, you read on you find that Snopes says that eating poinsettia leaves may cause ‘occasional vomiting’ and it quotes the Minnesota Poison Control Center as saying ‘when eaten in quantity, they may cause stomach upset’.

It is perfectly rational and sensible to say poinsettia is poisonous but the toxicity is so low that there is very little chance of anyone ingesting a sufficient quantity of the plant to produce symptoms. After all, that is the sort of comment that gets made of all manner of poisonous plants that have only very low levels of toxins. So, why are people so reluctant to say this when it comes to this particular plant?

It may be that, following the wrongly diagnosed case in 1919, there was a campaign to get the sale of poinsettias by florists banned. Since that time the horticultural industry, especially in the USA, has been sensitive to any suggestion that people should not buy one or more poinsettias to decorate the home at Christmas.

It is said that poinsettias were first part of Christmas in 16th century Mexico when a poor girl was told by an angel to offer weeds as a gift and the angel turned the leaves into a beautiful red display. It was introduced to the USA in 1828 and though it achieved some popularity it was not until the 1950s that plant breeders started trying to produce a plant that would rapidly grow into a small bush covered in the red leaves. Very clearly, the ‘tradition’ of having poinsettia in the house at Christmas was commercially driven.

Given that the plant is difficult to keep from one year to the next and it is even more difficult to get it to produce its characteristics red leaves after the first year, it is an ideal plant for retailers as most people will buy new each year.

So sensitive to the term poisonous is the horticultural industry that it sponsored research that demonstrated that poinsettias caused no serious harm. The research correctly determined that the toxicity of the plant is very low but the conclusion that poinsettias were not poisonous looks like erring on the side of the sponsor’s interests.

Euphorbia pulcherrima, poinsettia is poisonous but, so what? It is as unlikely to cause harm as the other plants brought into the house at Christmas; Viscum album (mistletoe), Ilex aquifolium (holly) or Hedera helix (ivy).